Field of Invention
This invention relates to a display panel and a display device.
Related Art
With the progress of technologies, flat display panels have been widely applied to various kinds of fields. Because flat display devices have compact structure, low power consumption, less weight and less radiation, they gradually take the place of cathode ray tube (CRT) display devices and are widely applied to various electronic products, such as mobile phones, portable multimedia devices, notebooks, TVs and display screens.
Taking a conventional liquid crystal display (LCD) panel as an example, it comprises a thin film transistor (TFT) substrate, a color filter substrate and a liquid crystal layer. The TFT substrate and the color filter substrate are disposed oppositely, and the liquid crystal layer is disposed between the TFT substrate and the color filter substrate. In the competitive market, the requirements about the size of the display panel and the color saturation of the display are rapidly increased as well as the demands for the performance and stability of the TFT. The TFT with metal oxide-based semiconductor (MOSs) can be manufactured at room temperature. It has better current output characteristic, lower leakage current and better electron mobility that is ten times higher than the amorphous silicon TFT (a-Si TFT). Accordingly, the power consumption of such display panel is reduced and the operation frequency of such display panel can be raised. Therefore, the metal oxide-based TFT becomes the mainstream driving element for the display panel and device.
Although the metal oxide semiconductor layer possesses better electric property, the electric property of the metal oxide semiconductor layer will be impaired during the subsequent processes of the TFT. To avoid the electric property of the metal oxide semiconductor layer from being impaired, a protection layer can be added and disposed on the semiconductor layer of the TFT in the conventional art. Then, since the source and the drain of the TFT must contact the semiconductor layer, the source and the drain need to contact the semiconductor layer through the opening of the protection layer. However, the opening of the protection layer will increase the layout area of the source and the drain, and the overlap area between the source or drain and the gate will be thus increased. Therefore, the feedthrough voltage of the pixel will be raised or the aperture ratio will be decreased, so as to deteriorate the display quality.
Therefore, it is an important subject to provide a display panel and a display device whereby the feedthrough voltage of the pixel won't be raised and the aperture ratio won't be decreased under the disposition of the protection layer, so as to enhance the display quality.